Question

The power of a lens is -2.0 D.It is*

a.It is convex lens of focal length 50 cm

b.It is concave lens of focal length -40 cm

c.It is concave lens of focal length -20 cm

d.none of the above

​

Answer 1

Explanation:

a thanks for the point ok

Answer 2

ANSWER

f=50 cm=0.5 m

P=

f

1

=

0.5

1

=2 D

For convex lens, f>0⟹P>0

For concave lens, f<0,⟹P<0

Lens is convex in the first case and concave in the second case. Power is equal to 2 dioptre in the first case and -2